4 Ways to Add External JavaScript Files in React

React Hooks and other methods

Despite the wide availability of npm packages, at times, we might need to rely on a few external libraries that require us to import some JS files.

For features used across the application, we can simply add JS files to head using the <script> tag in our global index.html file.

However, for the features that are used in specific components, this makes no sense. Since React doesn’t support the <script> tag in Component, here are a few ways of appending JS files to specific components.

React-script-tag

This is the easiest way of loading JS files for a beginner.

React-script-tag is an npm package that provides a React <script> tag that supports universal rendering. All standard <script> attributes like async, src, type, and defer are supported, including onLoad and onError callbacks.

import ScriptTag from 'react-script-tag';

const Demo = props => (
<ScriptTag type="text/javascript" src="/path/to/resource.js" />
)

We also have an isHydrating flag, which is a boolean value. It defaults to false and must be true if the client is hydrate()ing the server render.

You can read more about hydrate() in the React docs.

React Helmet

Helmet is a React component that manages all your changes to the document head. It is another simple, beginner-friendly package that supports both server-side and client-side rendering.

Helmet takes plain HTML tags and outputs plain HTML tags.

Note: React Helmet is heavier than react-script-tag, so I wouldn’t recommend using it if your only purpose is to use script tags.

DOM Method

Though the above solutions are simple to achieve, it requires us to add additional packages that might bulk up our application. If you have some experience coding, then you can do:

If you are appending JS files in more than one component, it is best to have a custom file that returns a function to do this.

In your component:

If you don’t want to retain the appended JS file on page redirection/reload, you should remove the script in the componentDidUnmount lifecycle method. To achieve this:

And in your component:

React Hooks

If you are a fan of Hooks in React, then useEffect is a great way to append external JS files. You can read my article on using the Effect Hook.

To give a gist useEffect is similar to componentDidMount and componentDidUpdate life cycle methods in React class components.

If your effect returns a function, React will run it when it is time to clean up, basically the componentDidUnmount lifecycle method. This is where we will remove the appended script.

React allows us to build custom Hooks, which let us extract component logic into reusable functions. The logic to append an external JS file to a component could be stored as a custom Hook as below:

Which could be used in components as below:

import importScript from 'customHooks/importScript';

const Demo = props => {
  importScript("/path/to/resource.js");
}

Resources

Thanks for reading!